Debian non-US packages

Prior to the release of Debian 3.1, United States laws placed
restrictions on the export of certain defense articles, which,
unfortunately, included some types of cryptographic software.
PGP and SSH, among others, fell into this category.
It was legal however, to import such software into the US.

To prevent anyone from taking unnecessary legal risks, some Debian
packages were only available from a site in Leiden, The Netherlands, until
the release of Debian 3.1, which incorporates this software thanks to
changes in United States law.

You should not need the non-US archive unless you are using a version of
Debian from before Debian 3.1.